Well I have a set of 113 right now and am feeding them about 75 watts each off my HCCA orion amp and they handle it just fine. I cant see 100 being an issue as long as the amp is set properly.
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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer
Sound dampening will definitely help with a cleaner sound. Usually cures unwanted road noise or irritating rattles. I hate that rattling noise. It drives me crazy! Bottom line, sound dampening helps, but it doesn't replace the sound of a speaker. If you want better sound than change the speaker. (typically)
As far as your other 6.5" speakers you have tried... That's really funny that you mentioned Sony. I've had experience with them for sure. For the price they are alright, but it's no wonder why you were dissapointed. I can personally say that if your looking for "high-performance" car audio, then don't look in the direction of Sony.
The same dissapointment from the Infinity Reference series. The Infinity Kappa series is far better. Even better than the MB Quarts that you mentioned.... IMO. Of course I paid a bit more for the Infinity's than I would for those MB Quarts, but not much. How much of a deal are you getting for the MB's? You wouldn't be ordering them from this site would you? www.onlinecarstereo.com
I do like MB Quart speakers very much. Certainly not a bad choice. And if your going from the place stated above then they are a great buy for $85. (try to get one more in-expensive item for that free shipping!)
As for the wattage thing, you shouldn't have a problem with running 100 watts rms to each.
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Do whatever makes you happy in life without diminishing the happiness of others